Carburetor metering rod air motor



y 2, 1967 A. J. REIFEL 3,317,199

CARBURETOR METERING ROD AIR MOTOR Filed Feb. 2, 1966 2 Sheets-Sheet 1 I I L4 J y k I re? l: @4 3g] 56 20 i /3 INVENTOR F I G 2 ALLAN J. REIFEL ATTORNEY A. J. REIFEL 2 Sheets-Sheet FIG. 4.

ATTORNEY CARBURETOR METERING ROD AIR MOTOR 1966 May 2, 1967 Filed Feb.

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United States Patent Filed Feb. 2, 1966, Ser. No. 524,536 Claims. (Cl. 26l51) This invention relates to a carburetor. It relates in particular to a carburetor utilizing a controlled metering rod for more accurately regulating fuel flow to the carburetor mixing conduit.

In carburetors of the type contemplated, the fuel flow passing from the carburetor fuel bowl, to the mixing conduit, is regulated to some extent by a metering rod positioned in an orifice connecting the source of fuel with the mixing conduit. The primary purpose of a metering rod is to afford the carburetor a higher degree of efliciency, and economy of function under all engine operating conditions.

This purpose is achieved by regulating the position of the metering rod in the orifice to alter the flow of fuel passing into the carburetor discharge nozzle as the demand for fuel is varied by the engine. One such regulating means could include a mechanical linkage connected directly to the carburetor throttle and operable to alter the position of the metering rod directly as the throttle is adjusted. Another means often utilized, includes the pneumatic or air motor arrangement connected to a source of vacuum such as the engine inlet manifold, whereby variations in manifold vacuum are reflected in a comparable adjustment in the metering rod position.

It has been found that while the fuel metering rod above described is beneficial in many respects to carburetor operation, under some circumstances it is desirable that closer control be exercised to regulate fuel flow and consequently improve engine combustion. Further, where the air motor type arrangement is utilized, the reaction time lapsed between the need for a richer air-fuel mixture, and the delivery of sufiicient fuel to provide such a mixture is often undesirable. This follows since the usual air motor arrangement is designed to respond proportionately to the degree of manifold vacuum.

It has been found further that at certain engine speeds and loads, excessive fuel delivery to the carburetor discharge nozzle can result in an over-rich air fuel mixture and the creation of large amounts of unburned hydrocarbons which are discharged with engine exhaust fumes. Engine operation under such circumstances is not only uneconomical, it also tends to aggravate a frequently present problem of air pollution due to the emission of unburned hydro-carbons and other undesirable matter into the atmosphere.

It is therefore an object of the invention to provide an improved carburetor having fuel metering means adapted to provide a more eflicient and economical air fuel mixture to the engine. It is a further object to provide an automatic control for metering fuel to the carburetor to avoid formation of over-rich air fuel mixtures. Another object is to provide a fuel metering rod and motor actuating mechanism therefor, automatically adjustable in response to both engine condition and throttle position. The foregoing objects together with others not specifically enumerated will be clear to those skilled in the art from the following description.

The invention in brief relates to an air motor for a carburetor having a fuel bowl, a mixing conduit, a lever actuated throttle, and a metering rod co-operative with the fuel bowl to regulate fuel flow. The air motor is embodied in a rigid casing having opposed enclosing diaphragms to define a plenum connected to the engine intake manifold. Each diaphragm is connected to meter- 3,317,199 Patented May 2, 1967 ing rod through a non-rigid sliding joint comprising a spacer loosely engaging the respective diaphragms. A spring within the air motor actuates one of the diaphragms while the other diaphragm is connected to and is actuated by the throttle lever.

In the figures:

FIGURE 1 is a top view shown in partial cross-section of a carburetor embodying the present invention.

FIGURE 2 is an elevational view in cross-section of the carburetor shown in FIGURE 1.

FIGURE 3 is a segmentary view on an enlarged scale of a portion of the carburetor shown in FIGURE 2, and

FIGURE 4 is a further enlarged view of the air motor shown in FIGURE 3.

The invention is presently illustrated as incorporated into the body of a single barrel carburetor similar to that shown in United States Patent 3,189,331. It is understood however, that the description of the fuel metering device is primarily for the purpose of illustrating a particular structure which may be applied equally as well to other forms of carburetors such as the multi-barrel type and the like.

Referring to FIGURES l and 2, the carburetor shown consists essentially of a casing 10, which is formed with a fuel and air mixture conduit 12, a fuel bowl cover portion 14 from which depends an accelerating pump cylinder 16, an accelerating fuel passage 18, and a fuel well structure 20. Mixture conduit 12 is connected by a flange 13 to intake manifold M of an internal combustion engine E. In the lower part of the conduit 12 there is rotatably mounted a throttle valve 22 fixed to a throttle shaft 24 journalled in appropriately aligned apertures in body casting 10. In the upper portion of the fuel air mixture conduit 12 there is similarly mounted for rotational movement an unbalanced choke valve 26 fixed to a choke valve shaft 28, which is also journalled in aligned apertures through the body casing 10. The top of mixture conduit 12 is connected to an air filter 29, partially shown in cross-section in FIGURE 2. Between the upper and lower portions of the mixture conduit 12 is formed a venturi or air flow restricting surface portion 30. A small booster venturi 32 is formed integrally with body casting 10 and has an inner venturi surface 34 coaxially aligned with the mixture conduit 12 and the primary venturi surface 30.

A fuel "bowl 36 is fixed beneath fuel bowl cover 14 and is held with its rim against a gasket 38 compressed between the rim and matching portions of the fuel bowl cover 14. A float structure 40 is pivotally mounted from pin 42 journalled in a depending portion of fuel bowl cover 14. A lever arm of float lever 43 fixed to float 40, abuts the lower end of a needle valve 44 having an upper tapered end extending into a valve seat 46 of the inlet 47 to the fuel bowl 36.

operationally, fuel is forced under pressure by pump 50 from fuel tank 52, through fuel line 48, and to the carburetor inlet 47. When fuel level in bowl 36 is low, float 40 lowers commensurably, and lever 43 permits valve 44 to be displaced to an open position. Fuel then flows into bowl 36 until reaching a predetermined level. The needle valve 44 is closed by the upward urging of float lever 43 as the fuel level rises.

Referring to FIGURES 2 and 3, the lower end of fuel well 20 is closed by a threaded fitting 56 having a central orifice 69 which is formed to provide an annular metering jet for fuel flow from the fuel bowl 36 to mixture conduit 12. The upper end of fuel well 20 intersects fuel passage 58 directed downwardly into secondary venturi 32. A nozzle fitting 60 is held in the end of passage 58, one end of the fitting 60 extending into the secondary venturi 34. A perforated fuel emission tube 62 is supported within well 20.

A metering rod 66 is suspended within fuel well 20, having a tapered metering end 68 formed with varying diameters. The formed end 68 is positioned within the main fuel jet orifice 69 for operation in response to engine requirements. Flow of fuel through main orifice 69 is controlled by metering rod 66 and in accordance with that portion of the formed end 68 which is positioned within the orifice.

Metering rod end 68 is accurately formed and engages fuel orifice 69 to assure maximum fuel efiiciency. In particular, with the engine running at idle speed, the broad end of metering rod 66 fits closely with the adjoining walls of orifice 69 thereby defining the minimum annulus to allow a sufiiciently large fuel quantity to sustain the engine at idle speed. This will permit satisfactory engine operation without overenrichment of the fuel mixture, a condition which is known to promote excessive production of unburned hydro-carbons.

In accordance with the invention, the air motor for actuating metering rod 66 is hereafter described as being integral with, and received within a recess in the carburetor body. It is appreciated however, that the air motor structure might be assembled in any number of ways with the carburetor to achieve the desired function of regulating movement of the fuel metering rod in response to both throttle movement and engine vacuum. Referring to FIGURES 3 and 4, the air motor is shown formed within the well 71 in the carburetor body 10. Well 71 is basically cylindrical having an upper rim 72 and a peripheral seat 73 spaced from the rim. Seat 73 as shown may be tapered with respect to the walls of well 71 to provide a suitable seating and sealing surface against which diaphragm 74 is urged. Well 71 terminates in a lower chamber 76 having a seating boss 77 which includes a central opening 78 adapted to freely receive the upper end of metering rod 66.

A flexible diaphragm 79 is positioned at rim 72 by an insertable spring washer 81 thereby forming a fluid tight seal between the diaphragm 79 and rim 72 to establish a plenum chamber within well 71.

Diaphragm 79 is provided with a fitting 85 including cap 83 on the outerside of the diaphragm, and a guide pin 84 disposed at the inner side within the plenum chamber. An adjustable bracket or stop means 86 is positioned on body having an outwardly projecting portion overhanging fitting 85 to limit upward movement of the diaphragm 79. Bracket 86 includes an adjusting screw 87 for varying the horizontal position of the overhanging portion when the carburetor is being calibrated to limit movement of diaphragm 79. Diaphragm 74, similar to diaphragm 79, is formed of flexible material such as reinforced rubber or the like. The outer edge of diaphragm 74 is urged into sealing engagement with peripheral seat 73 thereby forming a fluid tight joint. Diaphragm 74 includes a central fitting 88 having an outer hub 89 adapted to receive the end of metering rod 66. The inner end of fitting 88 includes a guide pin 91 diametrically opposite to guide pin 84.

A sleeve or spacer 92 including opposed end openings is received on the respective guide pins 84 and 91. Sleeve 92 may be deformed or otherwise fixedly positioned on guide pin 84, the sleeve is however slidably received on guide pin 91 to permit controlled reciprocable movement of diaphragm 74 in response to pressure variations within the plenum chamber. The latter is communicated with the engine intake manifold through a conduit not presently shown and opening at port 93. Sleeve 92 is preferably a metallic, tubular member of other suitable material. Said member is however of a predetermined length such that the lower end in sliding engagement with guide pin 91, will abut flange 94 of fitting 88 when diaphragm 74 is retracted to its innermost position.

A retainer 96 includes lower lip 97, and an elongated body which terminates at an opening 98 defined by an inturned rim 99 in registry with sleeve 92. A peripheral flange 101 depends outwardly from sleeve 92 having a receiving edge 103 adapted to engage the end of spring 104. Spring 104 is normally compressed and in engagement with retainer 96 to exert sufiicient pressure against the edge of diaphragm 74 to maintain a peripheral seal at the latter. Spring 94 exercises the additional function of urging sleeve 92 and consequently diaphragm 79, into the maximum upward position during all phases of operation of the air motor.

A second spring 106 surrounds the lower portion of sleeve 92, being in abutment with inturned rim 99 and flange 94 for normally biasing diaphragm 74 to an expanded position thereby overcoming the vacuum force established in the plenum in response to conditions in the engine intake manifold.

Retainer 96 may be perforated or, as shown in FIGURE 4 be provided with an enlarged opening 98 greater than the diameter of sleeve 92. This in effect communicates the plenum in well 71 with the interior of the retainer. The retainer 96 however, could be so constructed as to provide a sealed chamber therein segregated from the remainder of the plenum. In the latter instance, port 93 would of course be communicated with the inner portion of retainer 96, and opening 98 be provided with a sliding seal.

In the following automatic carburetor construction, the throttle valve 22 is actuated by a suitable linkage operable to rotate the throttle plate. As shown particularly in FIGURES 1 and 2 the direct connection between the present throttle valve 22 and the air motor, is provided through a throttle bracket 64 attached to shaft 24 for rotating the latter. Bracket 64 is further communicated directly through a suitable linkage to a connecting element 67 pivotably mounted to the carburetor body and actuating throttle lever 63. The latter includes a bifurcated end having an arcuate surface disposed in abutting contact with a ring 65 carried at the upper end of cap 83 which positions a spring 82 against a second ring 80. Thus, spring 82 normally bears against the bifurcated end of lever 63 and provides an overtravel connection to absorb further movement of lever 63 after metering rod 66 has reached its maximum depressed position.

Illustrative of the disclosed air motor and referring to FIGURES 3 and 4, with the engine at rest, there will be no manifold vacuum and the air motor components will assume the positions shown in FIGURE 4, with metering rod 66 urged to its maximum depth in orifice 69.

At engine cranking and start-up, maximum vacuum will be immediately created in intake manifold M, which vacuum is transmitted to the air motor plenum. Metering rod 66 is thereby withdrawn upwardly as diaphragm 74 is moved upwardly, thus positioning the widest portion of rod end 68 in orifice 69. The annular passage thus defined is calibrated to be suificiently large to pass just enough fuel to maintain the engine at idle speed. At idle however, throttle 22 will not be depressed to any substantial degree and consequently throttle lever 63 will be in withdrawn position abutting bracket 86 to maintain diaphragm 79 at its maximum upward position.

At engine idle, intake manifold vacuum will achieve approximately 25 inches mercury thus exerting a sufficient force to withdraw both diaphragms 79 and 74 to the withdrawn position within the plenum chamber. The compressive force of spring 104 however is adequate to maintain diaphragm 79 in the upward position against the plenum vacuum. Diaphragm 79 is thus influenced by the movement of lever 63 only.

In this position, spring 106 is fully compressed and flange 94 is disposed in engagement with the lower end of sleeve 92. As the throttle plate is further actuated to a partially open position, engine speed will increase and consequently lower the position of diaphragm 79 a distance directly proportionately to the movement of the throttle lever 63. Also, since manifold vacuum decreases at part open throttle to the value of about 10 to 15 inches of mercury, diaphragm 74 will assume a position similar to that shown in FIGURE 3. More particularly, diaphragm 74 is urged outwardly from the plenum thus positioning a narrower portion of rod end 68 in orifice 69. At wide open throttle, diaphragm 79 will be fully depressed as lever 63 has moved to its maximum displacement and hub 89 will bear against the seating boss 77 as shown in FIGURE 4 thus positioning metering rod end 68 as to define the maximum annulus in orifice 69. In effect, a direct linkage between throttle lever 63 and metering rod 66 is established, due to the rigidity of tube 92. As the engine speed varies slightly within normal cruising range, metering rod 66 will be subjected to axial movement directly in proportion to the displacement of throttle lever 63.

Now however, assuming the condition of a partially open throttle where the engine is subject to an added load, that is; when the vehicle approaches an upgrade, the engine will slow down. The resulting decrease in intake manifold vacuum without a compensating adjustment in the throttle, will decrease the plenum vacuum and permit diaphragm 74 and metering rod 66 to drop slightly. This slight drop causes flange 94 to disengage from the lower surface of tube 92 such that diaphragm 74 is free to operate separately and independently of the throttle, and entirely in response to engine manifold vacuum.

The lowering of diaphragm 74 adjusts metering rod 66 commensurably to reposition end 68 and increase the fuel flow annulus formed in orifice 69. This additional provision for fuel without added throttle opening, provides a slightly enriched air fuel mixture and consequently an automatic increase in the engine speed.

During slowing down and stopping of the engine, as throttle lever 63 moves to the closed throttle position the compressive force of spring 106 will be relaxed. However, with the resulting decrease in engine intake manifold vacuum which is reflected in the plenum, diaphragm 74 is again snapped to its maximum withdrawn position thereby moving metering rod 66 to its preferred location in orifice 69, to permit an optimum idle fuel feed.

The present invention thus provides a novel carburetor arrangement in which the metering rod actuator is-subject to both throttle adjustment and also to intake manifold vacuum. Although both of these forces have heretofore been utilized separately to regulate the metering rod, the combination presently disclosed provides a composite of the best features of each of said systems. Thus, not only is more eflicient engine operation realized simultaneously with a more etficient usage of fuel to reduce the detrimental effect of unburned hydrocarbons in the air.

It is clear to those skilled in the art that the herein disclosed carburetor and metering rod actuator describe a preferred embodiment of the invention which might be varied within limits without departing from the spirit and scope of the invention.

I claim:

1. An air motor for a carburetor having a fuel bowl, a mixing conduit, a lever actuated throttle, a metering rod registered in a fuel orifice for controlling fuel flow from said fuel bowl to said mixing conduit, and means positioning said air motor on said carburetor, said air motor including, a casing having a rigid wall, diaphragms sealed at diametrally opposed ends of said casing defining an expandable fluid tight chamber therebetween, means communicating said fluid tight chamber to a source of engine vacuum, guide means carried at the inner side of each of said opposed diaphragms, a spacer disposed longitudinally of said casing and slidably supported on said guide means, said spacer being of suflicient length to limit movement of the respective diaphragms toward each other into said fluid tight chamber, a first spring in said chamber biasing one of said diaphragms outwardly therefrom, a spring retainer in said chamber, a second spring engaging said spring retainer and having one spring end thereof in abutment with the other of said diaphragms to normally bias the latter in a direction outwardly from the chamber, said means positioning said air motor on said carburetor being disposed such that said throttle lever operably engages said one of said diaphragms to displace the latter, and said other diaphragm being in engagement with said metering rod for actuating the same whereby said metering rod is adjusted in said orifice in response to both the degree of engine vacuum, and to movement of said throttle lever.

2. An air motor as defined in claim 1 wherein said spring retainer disposed in said chamber is substantially concentric with said spacer.

3. In an air motor as defined in claim 1 wherein said first spring is disposed in compressive engagement with said spring retainer for urging the latter toward said other diaphragm thereby forming a fluid tight seal.

4. In an air motor as defined in claim 1 wherein said spring retainer includes a generally elongated body terminated at a peripheral lip, said lip being positioned against said other diaphragm to form a liquid tight seal, and said first spring compressibly engages said retainer peripheral lip to form a fluid tight seal therewith.

5. In an air motor as defined in claim 1 wherein said first and second springs respectively are disposed externally of said spacer and substantially concentric therewith.

6. An air motor as defined in claim 1 including st-op means carried on said carburetor and engaging said one diaphragm to limit outward movement thereof from said chamber.

7. In an air motor as defined in claim 6 wherein said stop means is adjustable to limit the movement of said diaphragm away from said chamber.

8. In an air motor as defined in claim 1 wherein said spacer includes openings formed at opposed ends thereof for engaging said respective guide means on each of said diaphragms.

9. In an air motor as defined in claim 1 wherein said spacer is fixed to at least one of said guide means and slidably guided on the other.

10. In an air motor as defined in claim 1 wherein said spacer includes an elongated tubular member having one end fixed to the guide means on said one diaphragm and having the other end slidably engaging said guide means on said other diaphragm. 7

References Cited by the Examiner UNITED STATES PATENTS 2,395,554 2/1946 Jones 26151 X 2,554,660 5/1951 Carlson 261-51 X 3,149,184 9/1964 Szwargulski 261-69 X 3,189,331 6/ 1965 Szwargulski 26169 X 3,189,333 6/ 1965 Kalert, et a1. 261-69 HARRY B. THORNTON, Primwry Examiner.

R. R. WEAVER, Assistant Examiner. 

1. AN AIR MOTOR FOR A CARBURETOR HAVING A FUEL BOWL, A MIXING CONDUIT, A LEVER ACTUATED THROTTLE, A METERING ROD REGISTERED IN A FUEL ORIFICE FOR CONTROLLING FUEL FLOW FROM SAID FUEL BOWL TO SAID MIXING CONDUIT, AND MEANS POSITIONING SAID AIR MOTOR ON SAID CARBURETOR, SAID AIR MOTOR INCLUDING, A CASING HAVING A RIGID WALL, DIAPHRAGMS SEALED AT DIAMETRALLY OPPOSED ENDS OF SAID CASING DEFINING AN EXPANDABLE FLUID TIGHT CHAMBER THEREBETWEEN, MEANS COMMUNICATING SAID FLUID TIGHT CHAMBER TO A SOURCE OF ENGINE VACUUM, GUIDE MEANS CARRIED AT THE INNER SIDE OF EACH OF SAID OPPOSED DIAPHRAGMS, A SPACER DISPOSED LONGITUDINALLY OF SAID CASING AND SLIDABLY SUPPORTED ON SAID GUIDE MEANS, SAID SPACER BEING OF SUFFICIENT LENGTH TO LIMIT MOVEMENT OF THE RESPECTIVE DIAPHRAGMS TOWARD EACH OTHER INTO SAID FLUID TIGHT CHAMBER, A FIRST SPRING IN SAID CHAMBER BIASING ONE OF SAID DIAPHRAGMS OUTWARDLY THEREFROM, A SPRING RETAINER IN SAID CHAMBER, A SECOND SPRING ENGAGING SAID SPRING RETAINER AND HAVING ONE SPRING END THEREOF IN ABUTMENT WITH THE OTHER OF SAID DIAPHRAGMS TO NORMALLY BIAS THE LATTER IN A DIRECTION OUTWARDLY FROM THE CHAMBER, SAID MEANS POSITIONING SAID AIR MOTOR ON SAID CARBURETOR BEING DISPOSED SUCH THAT SAID THROTTLE LEVER OPERABLY ENGAGES SAID ONE OF SAID DIAPHRAGMS TO DISPLACE THE LATTER, AND SAID OTHER DIAPHRAGM BEING IN ENGAGEMENT WITH SAID METERING ROD FOR ACTUATING THE SAME WHEREBY SAID METERING ROD IS ADJUSTED IN SAID ORIFICE IN RESPONSE TO BOTH THE DEGREE OF ENGINE VACUUM, AND TO MOVEMENT OF SAID THROTTLE LEVER. 